Conventionally, a full-color liquid crystal display device has been realizing a full-color display by (i) dividing each pixel of a transmissive liquid crystal display element into three picture elements, (ii) attaching red (R), green (G), and blue (B) color filters to the respective three picture elements, (iii) emitting, from a backlight, white lights to the three picture elements, and (iv) controlling, by supplying voltage application signals to liquid crystal cells of the three picture elements, transmittance of each of the white lights which pass through the three picture elements.
However, since each of the R, G, and B color filters transmits a light of its corresponding waveband and absorbs a light of other waveband, the liquid crystal display device including the color filters suffers from a loss of approximately two-thirds of lights. That is, the liquid crystal display device including the color filters has a low use efficiency of lights. Note here that, although there has been a field sequential color method which is one of full-color display methods using no color filters, the field sequential color method has a problem in which color breakup occurs.
Meanwhile, there has been proposed a display device which includes a backlight device and a transmissive modulation element (refer to Patent Literature 1). The backlight device includes LEDs (light emitting diodes) serving as light sources, and improves a use efficiency of lights. The display device includes (i) an image display element (liquid crystal panel) which (a) has two-dimensionally arranged apertures, each of which can be controlled so as to transmit a light of each color at a controlled rate and (b) is capable of modulating transmitted lights, (ii) a light path synthesizing optical system including a number of pairs of microlenses arranged two-dimensionally, each of which microlenses has front and back surfaces serving as convex lenses, (iii) an illumination optical system for emitting chief rays of different colors toward the light path synthesizing optical system at different angles, and (iv) a plurality of light sources for emitting lights of different colors.
The display device described in Patent Literature 1 can be configured such that (i) lights of different colors from the plurality of light sources, which are subjected to an effect of the illumination optical system, enter the light path synthesizing optical system such that their chief rays are at respective different angles to the light path synthesizing optical system and (ii) the lights of different colors are converged on their corresponding apertures of the image display element through a refraction effect of the light path synthesizing optical system. Accordingly, it is possible to (a) divide each pixel into three picture elements and (b) converge lights of different colors on the respective three picture elements (i.e., it is possible to achieve color separation of each pixel by colored lights). According to Patent Literature 1, no color filters are necessary and therefore a light loss does not occur, provided that an ideal color separation is achieved. Note, however, that Patent Literature 1 does not exclude provision of color filters for preventing colors from being accidentally mixed due to light leakage resulting from an undesirable result of the color separation.